[0001] This invention relates to broadcast signal receivers.
[0002] As is known, current video tape recorders include an internal clock which identifies
the current date and time, and which is operable to be used in conjunction with a
programmed record setting which provides the function of allowing a user to set the
video tape recorder to record a video signal transmitted over a designated channel
at a specific future date or time. Currently, the internal clock of a video tape recorder
is manually set by users who perform various steps specific to this time setting operation.
Since timer recording of a video tape recorder operates as a function of the time
indicated by its internal clock, the internal clock must be both manually and correctly
set by the user in order for the proper "time" recording of "programmed" broadcast
signals.
[0003] One problem encountered in a typical video tape recorder is the general difficulty
in setting its internal clock. Because of such difficulty, many users elect not to
set the internal clock, which results in a constant display of 12:00 PM on the video
tape recorder's display. Besides providing an undesirable display, an internal clock
which has not been properly set obviates the effective use of the video tape recorder's
program recording functions. Another difficulty with current video tape recorders
is the necessity of adjusting (i.e., resetting) the internal clock when it stores
an incorrect time. Such an incorrect stored internal time may be caused by the removal
of power to the video tape recorder (and without a proper back up power supply), incorrect
time keeping by the internal clock, or a change between daylight saving time and standard
time. In such cases, the video tape recorder user must again set the internal clock
to the correct time. In addition, an incorrect clock results in an incorrect recording
time when recording is initiated via a timer record function.
[0004] Documents which relate to the technological background of the present invention include
US Patents Nos. US-A-4 329 684, US-A-4 390 901, US-A-4 499 179, and US-A-4 635 121.
[0005] Various different aspects of the invention are set out in claims 1, 16, 21, 31 and
35 hereof.
[0006] In accordance with a preferred embodiment of the invention, a broadcast signal receiver
(e.g. a video tape recorder) which has an internal clock is tuned to a broadcast signal
having time data which indicates the local time. The tuned broadcast signal is supplied
as a tuned output signal from which the time data is extracted and used to automatically
set the internal clock of the broadcast signal receiver to the local time indicated
by the time data.
[0007] According to various preferred features of the embodiment, the internal clock is
set to the local time after the broadcast signal receiver is turned off, when the
internal clock is set to the local time at some predetermined time, when the difference
between the internal clock time and the local time is below a predetermined threshold
amount, when the difference between a programmed time for recording and the internal
clock time is greater than another predetermined threshold amount, when the internal
clock was not previously set, or when there is a change in the local time between
daylight saving time and standard time.
[0008] The preferred embodiment provides:
a broadcast signal receiver in which an internal clock is set automatically;
an apparatus and corresponding method wherein an internal clock is automatically
set, thereby eliminating the need manually to set that clock;
automatic setting of an internal clock of a broadcast signal receiver in the event
that the internal clock displays an incorrect time;
automatic setting of an internal clock of a broadcast signal receiver when the
current local time is different from the time indicated by the internal clock due,
for example, to a change between daylight saving time and standard time; and
an apparatus and method for automatically setting an internal clock in a broadcast
signal receiver.
[0009] The invention will now be further described, by way of illustrative and non-limiting
example, with reference to the accompanying drawings, in which like reference numerals
denote like elements and parts throughout, and in which:
Fig. 1 is a block diagram of a cable box and a video tape recorder in which the invention
can readily be embodied;
Fig. 2A is a timing diagram of a broadcast video signal and Fig. 2B is a schematic
diagram illustrating types of data supplied in the broadcast signal;
Fig. 3 is a flow chart of the operation of a broadcast signal receiver embodying the
invention;
Fig. 4 is a flow chart illustrating the operation of another embodiment of the invention;
Fig. 5 is a flow chart illustrating the operation of a further embodiment of the invention;
Fig. 6 is a block diagram of a cable box and a video tape recorder in accordance with
another embodiment of the invention; and
Figs. 7A to 7D are time charts used to explain the operation of an embodiment of the
invention.
[0010] Fig. 1 shows a broadcast signal receiver apparatus embodying the invention, the apparatus
including a cable box 1 and a video tape recorder 2. Cable box 1 provides external
broadcast signal receiving and tuning means and includes a tuner 12, a tuner control
microcomputer 13, a remote control receiver 14, and an RF modulator 15. Tuner 12 receives
a cable television (CATV) signal which is supplied to input terminal 11, as from a
cable broadcasting company. In addition to tuning to a selected channel, tuner 12
generally is further operable to descramble selected scrambled channels. Tuner 12
tunes to a selected channel of the CATV signal in accordance with a control signal
supplied by tuner control microcomputer 13, the channel being selected by a user and
represented by a control signal supplied by remote control receiver 14. Remote control
receiver 14 receives a remote control signal (e.g., an infrared signal) from a remote
control unit 4 (to be described) operated by the user. Tuner 12 tunes to the selected
channel and supplies the corresponding video signal to RF modulator 15 which converts
the video signal into a broadcast signal. The broadcast signal is supplied to video
tape recorder 2. The operation of cable box 1 is well known in the art, and therefore,
further description of such operation is omitted, except where necessary for an understanding
of embodiments of the invention.
[0011] Video tape recorder 2 is comprised of a tuner 20, a data decoder 21, a tuner/clock
control microcomputer 22, a display control 23, a record/playback processing circuit
24, an RF modulator 25, a cable box controller 26, a mechanical controller 27, and
magnetic heads 28. Tuner 20 is operable to receive the broadcast signal supplied by
cable box 1, and is also operable to receive broadcast signals supplied by an external
antenna 5. Tuner 20 tunes to a selected channel in accordance with a control signal
supplied thereto by microcomputer 22, and supplies the signals on the selected channel
to data decoder 21 and record/playback processing circuit 24. It is appreciated that
tuner 20 performs a tuning function similar to that performed by tuner 12 in cable
box 1.
[0012] The broadcast signal, which is an NTSC video signal, supplied to data decoder 21
may contain "captioned" data inserted into predetermined horizontal lines of each
vertical line interval of the NTSC video signal. Fig. 2A illustrates an NTSC video
signal having captioned data. As shown, a predetermined line interval in the vertical
blanking interval is comprised of a horizontal synchronizing signal HD followed by
a color burst signal SC, seven cycles of a clock run-in signal (503 KHz), three bits
S1, S2 and S3, and 16 bits of data known as "NRZ" data. The clock run-in signal provides
synchronization for the reading of the NRZ data which follows bits S1-S3 formed of
two low bits S1 and S2 and high bit S3 (i.e., the start bit). The NRZ data is composed
of two 8 bit groups wherein each group includes a seven bit ASCII character b1-b7
and a parity bit p.
[0013] Returning to Fig. 1, data decoder 21 extracts the NRZ data from the video signal
and decodes the NRZ data (which may be represented as a hexadecimal code) into a binary
coded decimal (BCD) code. The decoded captioned data is supplied to microcomputer
22 which stores the decoded captioned data in a random access memory (RAM) (not shown).
Microcomputer 22 supplies the captioned data to display control circuit 23 which converts
the decoded captioned data into character data (e.g., dot data), and microcomputer
22 also supplies to display control circuit 23 a position control signal which indicates
the location at which the character data is to be superimposed on the video image.
The position control signal represents a desired position of the video picture, e.g.
left top corner, right top corner, left bottom corner, right bottom corner, center,
etc. Display control circuit 23 receives from record/playback processing circuit 24
the broadcast video signal and superimposes the character data (i.e., captioned data)
on the video signal at the position indicated by the position control signal. The
resulting video signal is supplied to RF modulator 25 which converts the video signal
and superimposed character data into a signal displayable on television monitor 3.
Accordingly, character data or "captions" are superimposed on broadcast video signals
displayed on television monitor 3.
[0014] Microcomputer 22 further operates as a channel selection controller which supplies
a selected channel control signal to cable box controller 26, the selected channel
being either a manually selected channel (e.g., a user manually selects the channel
via a remote control device) or a preprogrammed channel. In response to the control
signal from microcomputer 22, cable box controller 26 supplies a control drive signal
to remote control unit 4, which supplies a remote control signal to cable box 1, and
this, in turn, operates to tune the cable box to the selected channel as previously
described. In addition to controlling the channel selection (i.e. tuning) by tuner
12 in cable box 1 and tuner 20 of video tape recorder 2, microcomputer 22 further
is operable to provide power on and off control of cable box 1 via cable box controller
26 and remote control unit 4. In addition, microcomputer 22 is operable to set an
internal clock included in the tuner/clock control of microcomputer 22.
[0015] Mechanical controller 27 provides the drive control of the recording/reproducing
heads, and video and tape feeder portions of video tape recorder 2, the operation
of which being well known in the art. For example, the mechanical controller controls
play, fast forward, rewind, slow motion, record and similar functions.
[0016] During a recording operation of video tape recorder 2, record/playback processing
circuit 24 process the video signal supplied by tuner 20 to form a record signal.
A magnetic head 28 of video tape recorder 2 records the record signal onto a magnetic
tape 29 loaded into video tape recorder 2. Similarly, during a playback operation
of video tape recorder 2, record/playback processing circuit 24 in conjunction with
magnetic head 28 reproduces the video signal recorded on magnetic tape 29, and supplies
the reproduced video signal to display control circuit 23. The video signal may then
be displayed on television monitor 3 via RF modulator 25.
[0017] Referring back to Fig. 2A, captioned data is multiplexed on selected horizontal lines
of each (or selected) vertical line interval of the broadcast video signal. Other
"special" information, known as VBI data, may similarly be multiplexed onto the broadcast
signal. VBI data may include, for example, time data indicating the current time of
day and whether the current time is daylight saving time or standard time, as well
as, current and future program information which may include a program's start time,
its elapsed time, and its content. VBI data may further include information about
the station broadcasting the broadcast signal, as well as weather and news information.
[0018] Fig. 2B illustrates the data structure of captioned data and VBI data included in
a vertical line interval of the broadcast signal. As shown, VBI data multiplexed in
a horizontal line interval of the vertical line interval is composed of 16 bits of
NRZ data, which includes 7 bits of data b1 to b7, a parity bit p, followed by another
7 bits of data b1 to b7 and another parity bit p. These first 16 bits of VBI data,
which represent a first "line", indicate a start code and the type of VBI data. In
particular, the first 7 bits b1 to b7 indicate a "class" of the VBI data (to be described),
and the latter 7 bits b1 to b7 identify the type of data within the indicated class.
Successive VBI data in following lines of the vertical blanking interval (i.e., the
successive lines) represent data pertaining to the class/type identified in the first
line of the VBI data.
[0019] If the transmission of VBI data is interrupted by the transmission of captioned data,
the transmission of the remaining VBI data will continue upon termination of the captioned
data transmission. In this instance, the first 7 bits of VBI data which follows the
captioned data represents a continuation code, and is followed by the seven bits b1
to b7 which repeat the type of the VBI data. Upon completion of the transmission of
the VBI data, one final line of VBI data is transmitted which includes a 7 bit end
code, a parity bit, a 7 bit checksum code and another parity bit.
[0020] Examples of VBI data classes include "current program information" and "future program
information", and the type of data that may be available in each class includes "program
start time", "length/time elapsed", "program title", "program type", "program audience",
etc. Another class is "channel information" which represents special information about
the selected channel (other than the broadcast program) and the type of data that
may be available in this class includes "network name", "station ID", "tape delay"
(which represents the delay in hours and minutes of the network program delivered
for broadcast by the local station), etc. The VBI data may also be identified by the
class "miscellaneous information", and the type of data that may be available in this
class includes "Greenwich time", "local time zone", "daylight saving time use", etc.
Another possible class is "public service/weather service/message", and the type of
data that may be available in this class includes "weather service". For present purposes
the primary concern is with data included in the "miscellaneous information" class,
and hereinafter this data is identified as "time data".
[0021] Fig. 3 is a flow chart illustrating the operation of the broadcast signal receiver
embodying the invention and represents the instructions performed by microcomputer
22 of video tape recorder 2 for automatically setting the internal clock of video
tape recorder 2. As shown, the operation of automatically setting the internal clock
begins when video tape recorder 2 is manually turned off by a user, wherein cable
box 1 is turned on in response to a control signal from remote control unit 4, as
represented by instruction ST1. After cable box 1 is turned on, microcomputer 22 supplies
a second control signal to cable box 1 via cable box controller 26 and remote control
unit 4 instructing tuner 12 in cable box 1 to tune to a selected predetermined channel
whose broadcast signal contains VBI data which includes time data, as shown by instruction
ST2. As is appreciated, when cable box 1 is not present to receive broadcast signals,
microcomputer 22 controls tuner 20 in video tape recorder 2 to tune to this predetermined
channel. Then, as represented by instruction ST3, microcomputer 22 via data decoder
21 extracts the time data from the VBI data included in the received broadcast signal.
In a preferred embodiment, the time data indicates Greenwich time or local time, and
further indicates whether local time is daylight saving time or standard time. It
is appreciated that the VBI data may contain both Greenwich time and local time, and
may also contain the current calendar date (it is appreciated that a change from or
to daylight saving time may be determined from the current calendar date and time).
Microcomputer 22 sets the internal clock of video tape recorder 2 to the local time,
as represented by instruction ST4, whereupon cable box 1 is turned off, as shown by
instruction ST5.
[0022] It is appreciated that when a user turns off cable box 1 and video tape recorder
2, power nevertheless remains supplied to various components of video tape recorder
2 so that the internal clock may be automatically set, and upon completion of setting
the internal clock, power may be removed. Since the operation of automatically setting
the internal clock requires that time data be received and such time data is included
only on selected broadcast signals, causing the tuner to tune to the selected broadcast
signal while video tape recorder 2 is on (i.e., the user has not manually turned off
video tape recorder 2) causes an undesirable change in the channel selection. Such
a change in channel selection during the operation of video tape recorder 2 may cause
either interrupted viewing of a selected channel or an interruption of the recording
of a broadcast program. Accordingly, these undesirable interruptions are avoided by
deferring the automatic setting of the internal clock control after the video tape
recorder 2 is turned off.
[0023] Fig. 4 is a flow chart illustrating another broadcast signal receiver embodying the
invention, wherein those instructions shown in Fig. 4 which correspond to the same
instructions shown in Fig. 3 are denoted by the same reference numerals. After video
tape recorder 2 is turned off, cable box 1 is turned on and then controlled to tune
to the predetermined channel whose broadcast signal contains the VBI (time) data.
As before, the time data is extracted from the broadcast signal, as represented by
instructions ST1, ST2, and ST3, respectively, in a manner similar to that described
with reference to Fig. 3.
[0024] After the time data is extracted from the broadcast signal, microcomputer 22 determines
whether the current operation of automatically setting the internal clock represents
the initial setting of the internal clock, as represented by inquiry ST6. That is,
microcomputer 22 determines if the internal clock was previously set. If it is determined
that the current operation is the initial setting of the internal clock, then microcomputer
22 sets the internal clock to the local time, as represented by instruction ST4 and
as has been described above. If not, microcomputer 22 determines whether the difference
in time between the local time indicated in the extracted time data and the internal
clock time is below a predetermined threshold level T (e.g., 10 minutes), as represented
by inquiry ST7. If the determined difference is below the predetermined level T, microcomputer
22 sets the internal clock to the local time, as represented by instruction ST4. If
the determined difference is not below the predetermined level T, for example, if
the difference between the local time and the internal control time is greater than
10 minutes, microcomputer 22 then determines whether there was a change in the local
time (as represented by the extracted time data) between daylight saving time and
standard time, as represented by instruction ST8. If such a change is detected, microcomputer
22 sets the internal clock to the local time at instruction ST4. However, if there
was no change from or to daylight savings time, cable box 1 is turned off, as represented
by instruction ST5. Similarly, after completion of instruction ST4, cable box 1 is
turned off.
[0025] In the embodiment illustrated in Fig. 4, the internal clock is set to the local time
indicated in or derived from the extracted time data, except when the internal clock
had been previously set, the difference between the internal clock time and the local
time is greater than the predetermined level T, and there is no change from or to
daylight saving time. These conditions, which result in not setting the internal clock
to the local time, likely represent an incorrect local time due to "noise" or some
other problem in the transmission of the VBI data. As previously discussed, the internal
clock may indicate an incorrect time when there is a loss of power to the internal
clock or there is incorrect time keeping by the internal clock, such situations resulting
in the automatic setting of the internal clock to the local time after video tape
recorder 2 is turned off. Further, an incorrect internal clock time due to a change
in local time between daylight saving time and standard time also results in the automatic
setting of the internal clock.
[0026] Fig. 5 is a flow chart of the operation of a further broadcast signal receiver embodying
the invention. As shown, the operation of automatically setting the internal clock
to the local time is initiated when video tape recorder 2 is turned off, at which
time microcomputer 22 determines whether the existing amount of time before a "preprogrammed"
record setting begins recording is less than a predetermined time amount "t0" (e.g.,
5 minutes), as represented by inquiring ST9. That is, microcomputer 22 determines
the difference between the internal clock time and the "programmed time", wherein
the programmed time represents the time at which the recording of a broadcast program
is to begin. If it is determined that this difference in time is less than the predetermined
time amount t0, the operation for automatically setting the internal clock terminates.
However, if the calculated difference in time is greater than the predetermined time
amount t0, cable box 1 is turned on, as represented by instruction ST1, and the operation
of automatically setting the internal clock proceeds in the same manner shown in Fig.
4, previously described.
[0027] In the embodiment shown in Fig. 5, microcomputer 22 does not set the internal clock
when video tape recorder 2 is about to begin recording. This prevents the internal
clock from being set when there is a possibility that setting the internal clock may
cause a "skipping over" of the programmed record start time.
[0028] In the above described embodiments, the operation of automatically setting the internal
clock to the local time is initiated when video tape recorder 2 is turned off. However,
it is appreciated that such operations may be performed at a fixed time of each day
or at a fixed time and day of each month (or year) when video tape recorder 2 is not
on (i.e., not being used). Further, such operations may be performed at a fixed time
regardless of whether video tape recorder 2 is on or off. In addition, the above described
embodiments provide that cable box 1 is controlled to tune to a selected predetermined
channel. Accordingly, upon extracting the time data from the broadcast signal (instruction
ST3), it may be advantageous to control cable box 1 to tune to the channel to which
it was originally tuned prior to the initiation of the automatic setting operation.
[0029] Fig. 6 is another block diagram of a video tape recorder used with a cable box in
which the present invention finds ready application, wherein VBI data contained in
the broadcast signal includes time data which indicates a change between daylight
savings time and standard time. The embodiment shown in Fig. 6 is the same in all
respects to the embodiment shown in Fig. 1, except a microcomputer 22A responsive
to a change between daylight saving and standard time controls the operation of video
tape recorder 2, and therefore, the description of those parts shown in Fig. 6 that
are also shown in Fig. 1 are omitted.
[0030] In the embodiment shown in Fig. 6, microcomputer 22A detects a change from or to
daylight saving time based upon the time data in the VBI data. Figs. 7A to 7D illustrate
an example of the internal clock time and the local time when the local time changes
from standard time (also known as ordinary time) to daylight savings time. As shown
in Figs. 7A and 7B, both the internal clock time and local time are the same at 22:00
(10:00 PM) and 23:00 (11:00 PM). However, at a time "t1", which indicates when there
is a change from ordinary (standard) time to daylight saving time, as illustrated
in Fig. 7C, the local time is 1:00 (AM) while the internal clock time is 0:00 (12:00
PM), thus resulting in an incorrect internal clock time of one hour. Microcomputer
22A detects this change from standard time to daylight saving time, and accordingly
adjusts the internal clock to "gain" one hour at time tl. Fig. 7D illustrates the
internal clock time after it is adjusted (i.e., reset). Microcomputer 22A similarly
adjusts the internal clock when a change from daylight saving time to standard time
is detected by setting the internal clock "back" one hour. It is appreciated that
programmed recording operations are unaffected by a change of the internal clock time
to either standard time or daylight savings time. However, it may be desirable to
adjust a preprogrammed time of recording in a manner similar to the adjustment of
the internal clock time when there is a change between standard time and daylight
saving time. In this instance, the preprogrammed time is adjusted to "gain" one hour
when the local time changes from standard time to daylight saving time, and is adjusted
to "lose" one hour when the local time changes from daylight saving time to standard
time. For example, the preprogrammed start time of recording is 2:30 PM and the preprogrammed
stop time of recording is 3:30 PM, then the preprogrammed start time is changed to
1:30 PM and the preprogrammed stop time is changed to 2:30 PM when the local time
changes from standard time to daylight saving time.
[0031] In another embodiment of the present invention, the operation of automatically setting
the internal clock may be initiated after all of the programmed recording operations
are complete.
[0032] In accordance with the above disclosure, automatically setting the internal clock
ensures the proper timed operation of programmed record settings. In addition, good
operation is provided in areas utilizing daylight saving time since the additional
need of having to reset the internal clock at these time changes is obviated.
[0033] While the invention has been particularly shown and described in conjunction with
preferred embodiments thereof, it will be readily appreciated by those of ordinary
skill in the art that various changes may be made without departing from the scope
of the invention. For example, while the operation of automatically setting the internal
clock has been described in conjunction with a video tape recorder utilizing a cable
box which receives broadcast signals, the present invention is not limited in use
with a cable box and broadcast signals may be received directly via an antenna or
other known broadcast signal receiving means, thereby obviating the cable box.
[0034] As another example, although the VBI data is described as being multiplexed on the
video signal in a manner similar to the multiplexing of captioned data, the VBI data
may be transmitted with the broadcast signal in other manners. Further, the present
invention is not limited solely to VBI data with the disclosed format, but may utilize
VBI data in other formats.
[0035] Still further, although the present invention is described in conjunction with a
closed/captioned system, other systems, including a television receiver system, a
radio receiver system and a satellite broadcast receiver system, may be utilized with
the present invention.
[0036] Therefore, it is intended that the appended claims be interpreted as including the
embodiments described herein, the alternatives mentioned above and all equivalents
thereto.
1. A broadcast signal receiver having an internal clock indicating an internal clock
time, the receiver comprising:
means for receiving a plurality of broadcast signals;
tuning means (12/20) tunable to a predetermined one of said broadcast signals having
time data indicating a local time and supplying said predetermined one of said broadcast
signals as a tuned output signal;
means (22/22A) for extracting said time data from said tuned output signal; and
clock setting means (22/22A) responsive to said extracted time data for automatically
setting said internal clock to said local time.
2. A broadcast signal receiver according to claim 1, wherein said clock setting means
is operative to set said internal clock to said local time after said broadcast signal
receiver is turned off.
3. A broadcast signal receiver according to claim 1, wherein said clock setting means
is operative to set said internal clock to said local time at a fixed predetermined
internal clock time.
4. A broadcast signal receiver according to claim 3, wherein said clock setting means
is operative to set said internal clock to said local time at said fixed predetermined
time only if said broadcast signal receiver is turned off.
5. A broadcast signal receiver according to claim 1, comprising means for determining
a difference between said internal clock time and said local time, and wherein said
clock setting means is operative to set said internal clock to said local time only
when said determined difference is less than a predetermined threshold amount.
6. A broadcast signal receiver according to claim 1, comprising programmed recording
means for recording received broadcast signals on a record medium at a programmed
time.
7. A broadcast signal receiver according to claim 6, comprising means for determining
a difference between said programmed time and said internal clock time, and wherein
said clock setting means is operative to set said internal clock to said local time
only when said determined difference is greater than a predetermined threshold amount.
8. A broadcast signal receiver according to claim 1, comprising means for detecting a
change in said local time between daylight saving time and standard time, and means
for changing a programmed time in response to said change between daylight saving
time and standard time.
9. A broadcast signal receiver according to claim 1, wherein said clock setting means
is operative to set said internal clock to said local time if said internal clock
had not been previously set.
10. A broadcast signal receiver according to claim 1, comprising detecting means for detecting
when said local time indicated by said time data changes from daylight saving time
to standard time or from standard time to daylight saving time, and wherein said clock
setting means is operative to set said internal clock to said local time when said
change in said local time is detected by said detecting means.
11. A broadcast signal receiver according to claim 1, wherein said clock setting means
is operative to set said internal clock to said local time when said internal clock
time represents daylight saving time and said local time represents standard time.
12. A broadcast signal receiver according to claim 1, wherein said clock setting means
is operative to set said internal clock to said local time when said internal clock
time represents standard time and said local time represents daylight saving time.
13. A broadcast signal receiver according to claim 1, wherein said time data indicates
a change from standard time to daylight saving time, and said clock setting means
is operative to set said internal clock to said local time when there is a change
to daylight saving time.
14. A broadcast signal receiver according to claim 1, wherein: said time data includes
calendar data; the broadcast signal receiver comprises means for identifying a change
to daylight saving time in accordance with said calendar data; and said clock setting
means is operative to set said internal clock to said local time when said means for
identifying identifies said change to daylight saving time.
15. A broadcast signal receiver according to any one of the preceding claims, which is
a video tape recorder.
16. A broadcast signal receiver having an internal clock indicating an internal clock
time and being coupled to a tuner (12/20) having tuning means controllably tunable
to a selected one of a plurality of received broadcast signals and supplying said
selected one of said plurality of received broadcast signals to said broadcast signal
receiver, said broadcast signal receiver comprising:
channel selection means for controlling said tuner to tune to a predetermined broadcast
signal having time data indicating a local time;
means for receiving said predetermined broadcast signal from said tuner (12/20);
means (22/22A) for extracting said time data from said predetermined broadcast
signal; and
clock setting means (22/22A) responsive to said extracted time data for setting
said internal clock to said local time indicated by said time data.
17. A broadcast signal receiver according to claim 16, comprising means for turning said
tuner on after said broadcast signal receiver is turned off, and wherein said clock
setting means is operative to set said internal clock to said local time after said
broadcast signal receiver is turned off and said tuner is turned on.
18. A broadcast signal receiver according to claim 17, wherein said channel selection
means is operative to control said tuner to automatically tune to said predetermined
broadcast signal having said time data after said broadcast signal receiver is turned
off and said tuner is turned on, and to control said tuner to automatically tune to
a previous broadcast signal to which said tuner was previously tuned when said broadcast
signal receiver was turned off after said clock setting means sets said internal clock
to said local time indicated by said time data.
19. A broadcast signal receiver according to claim 18, comprising means for turning said
tuner off after said clock setting means sets said internal clock to said local time.
20. A broadcast signal receiver according to claim 16, wherein said channel selection
means is a remote control device (4) which remotely controls said tuner.
21. A method of setting an internal clock indicating an internal clock time in a broadcast
signal receiver, the method comprising the steps of:
receiving a plurality of broadcast signals;
tuning (12/20) to a predetermined one of said broadcast signals having time data
indicating a local time;
extracting (22/22A) said time data from said tuned broadcast signal; and
setting (22/22A) said internal clock to said local time indicated by said extracted
time data.
22. A method according to claim 21, wherein said internal clock is set to said local time
after said broadcast signal receiver is turned off.
23. A method according to claim 21, wherein said internal clock is set to said local time
at a fixed predetermined internal clock time.
24. A method according to claim 23, wherein said internal clock is set to said local time
at said fixed predetermined time only if said broadcast signal receiver is turned
off.
25. A method according to claim 21, comprising the step of determining a difference between
said internal clock time and said local time, and wherein said internal clock is set
to said local time only when said determined difference is less than a predetermined
threshold amount.
26. A method according to claim 21, wherein said broadcast signal receiver is operable
to record a broadcast signal at a programmed time, said method comprising the step
of determining a difference between said programmed time and said internal clock time,
and wherein said internal clock is set to said local time only when said determined
difference is greater than a predetermined threshold amount.
27. A method according to claim 21, wherein said internal clock is set to said local time
if said internal clock had not been previously set.
28. A method according to claim 21, comprising the step of detecting when said local time
indicated by said time data changes from daylight saving time to standard time or
from standard time to daylight saving time, and wherein said internal clock is set
to said local time when said change in said local time is detected.
29. A method according to claim 21, wherein said internal clock is set to said local time
when said internal clock time represents daylight saving time and said local time
represents standard time.
30. A method according to claim 21, wherein said internal clock is set to said local time
when said internal clock time represents standard time and said local time represents
daylight saving time.
31. A method of setting an internal clock indicating an internal clock time in a broadcast
signal receiver which receives a broadcast signal from a tuner, the method comprising
the steps of:
controlling said tuner (12/20) to tune to a predetermined broadcast signal having
time data indicating a local time;
extracting (22/22A) said time data from said predetermined broadcast signal; and
setting (22/22A) said internal clock to said local time as indicated by said extracted
time data.
32. A method according to claim 31, further comprising the step of turning said tuner
on after said broadcast signal receiver is turned off, and wherein said internal clock
is set to said local time after said broadcast signal receiver is turned off and said
tuner is turned on.
33. A method according to claim 32, wherein said step of controlling said tuner to tune
to said predetermined broadcast signal having said time data is carried out after
said broadcast signal receiver is turned off and said tuner is turned on, the method
comprising the step of controlling said tuner to tune to a previous broadcast signal
to which said tuner was previously tuned when said broadcast signal receiver was turned
off after said internal clock is set to said local time.
34. A method according to claim 33, comprising the step of turning said tuner off after
said internal clock is set to said local time.
35. A method of setting an internal clock indicating an internal clock time in a broadcast
signal receiver, the method comprising the steps of:
receiving a broadcast signal having time data indicating a local time;
extracting (22/22A) said time data from said broadcast signal;
determining if said internal clock had been previously set;
determining a difference between said internal clock time and said local time;
determining from said extracted time data if said local time had changed between
daylight saving time and standard time; and
setting (22/22A) said internal clock to said local time indicated by said time
data if said internal clock was previously set, or if said determined difference is
less than a predetermined threshold amount, or if said local time had changed between
daylight saving time and standard time.
36. A method according to claim 35, wherein said broadcast signal receiver is operable
to record a broadcast signal at a programmed time, said method comprising the step
of determining a difference between said programmed time and said internal clock time,
and wherein said step of setting said internal clock is prevented when said determined
difference is less than a predefined amount.